This is a follow-up study at 18-24 months corrected age of very low birthweight infants who were randomized to treatment with rhu GM-CSF or placebo in the efficacy protocol. The primary objective is to evaluate at 18 to 24 months corrected age, the neurodevelopmental status of very low birthweight infants treated with rhu GM-CSF or placebo. The secondary objectives are to 1) evaluate at 18 to 24 months corrected age, the medical status of very low birthweight infants previously treated with rhu GM-CSF or placebo. 2) evaluate at 18 to 24 months corrected age, the hematologic and immunologic status of very low birthweight infants previously treated with rhu GM-CSF or placebo. This study has just begun enrolling participants.